Q21 of 55 Page 361

A girl of mass 40 Kg climbs a rope 6 m long at constant speed in 15 seconds. What power does she expend during the climb?

Given,

Mass m = 40 kg


Height h = 6m


Time = 15 s


Power =????


Let g = 10 ms-2


Potential energy = m × g × h


= 40×10×6 J


= 2400 J




Power = 160 J/s


So power spent by girl is 600 watts


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